Stairs calculators - Wooden staircases in 3D, layouts, dimensions. Building Codes & Terminology

Stairs calculators - Wooden staircases in 3D, layouts, dimensions. Building Codes & Terminology

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Design and calculate perfect staircase with KALK.PRO

Building a staircase requires proper design, precise measurements and accurate calculations of a staircase so that it is safe and at the same time comfortable and practical.

To build the perfect stairs for a private dwelling, use our project, as well as the building codes currently in force in your country, region or state (local building-code requirements). With the KALK.PRO stairs calculators you can determine all- important stair dimensions - simply and quickly.

The unique KALK.PRO program is online tool with professional stair calculators: accurate drawings and layouts, all dimensions, interactive 3D models, templates, calculation of optimal material consumption.

In order to make your work with our stair project comfortable, we will give you the basic terms and definitions used in the calculation and staircase construction.

 

Types of staircase

When it comes to the stairs design, before choosing from the types of stairs design for your house you should consider some things — your budget, the available space for a staircase and types of material you'll be using.

Please remember : low quality building materials can be responsible for staircase collapse (contains wood imperfection — knots, cracks, checks and voids)

There are different kinds of stairs, classified by:

  • shape : straight flight staircases, stairs with a turn, continuous stairs, mixed stairs;
  • material : wooden staircase, metal, concrete, marble, etc.;
  • slope : ramp (0-15°), stairs (20-45°), ladders (more than 50°);
  • type of stair tread support : stringer stairs, floating stairs (mono stringer, cantilevered stair, suspended staircase).

Turning stairs are subclassified into:

  • Quarter landing stairs (L-shaped, 90-degree turn),
  • Half landing stairs, switchback (U-shaped, .180-degree turn),
  • Quarter turn winder staircase (L-shaped, 90-degree turn),
  • Half turn winder staircase or double winder staircase (U-shaped, 180-degree turn),
  • Z-shaped stairs.

Continuous stairs are divided into three categories:

  • circular stairs,
  • spiral stairs,
  • helical stairs.

Stairs can also be categorized according to the main types of tread support:

  • stringer stairs — mono stringer, double stringer or even three stringers; open stringer (sawtooth) or closed stringer (housed or routed);
  • cantilever staircase, suspended (treads are fixed only at one end);
  • bolted staircases.

 

Stair terminology, stair parts

Before designing your staircase, you need to know the main elements of the stairs and dimensions needed to be measured for the stairs calculation (manually or with our calculator).  Main parts and components of a staircase are:

  • Stair Treads – the horizontal surface of a stair step.
  • Rise – step height, the vertical distance between the top surfaces of adjacent treads.
  • Going (Run) – the horizontal distance between two vertical projections of successive nosings.
  • Tread Depth – Going or the tread run including the nosing projection (Pay attention, in Building codes “Tread Depth” is often used in meaning of Going, do not confuse these terms).
  • Step – the combination of a tread and riser.
  • Stair Riser – the vertical part of a step, forming the space between steps.
  • Nosing – the leading edge of the tread
  • Nosing Projection – overhang or protrusion, projection of the upper tread leading edge to the tread edge below.
  • Stair Stringer – the main structural stair component, diagonal boards supporting and holding the treads and risers, transfers loads to the structure.
  • Open Stringer – sawtooth stringer, zigzag shape (treads installation directly onto the stringers).
  • Closed Stringer – housed stringer (treads fit into routed channels in the stringer).
  • Total Rise – the vertical distance from the lower finished floor level to the upper finished floor level
  • Total Run – the horizontal length of stairway, from the end of the staircase with bottom stair nosing to the back of the riser on the top.
  • Balustrade – railing system (the complete assembly of handrails, balusters, newel posts).
  • Handrail – rail on top of the balusters for grasping with a hand
  • Balusters – vertical columns supporting a handrail, spindles
  • Newel Post – structural element of a staircase, vertical column connecting balustrade components, supporting the handrails, joining treads and stringers.
  • Headroom – the clear vertical space between the ceiling and the nosing line (to prevent striking the head).
  • Landing – platform at the top and bottom of the stairway, intermediate platform between flights, changing the direction of stairs.
  • Nosing line , Pitch line – line connecting the nosings of the treads.
  • Minimum stringer throat depth – stringer minimum width from the edge to the saw's teeth, it’s responsible for the structural capability (don’t overcut stair stringer)
  • Flight – a stairway, uninterrupted series of steps between landings or levels

A typical staircase is shown below with the main stair parts:

Picture of main stair parts diagram - kalk.pro

 

Stair rule of thumb formulas for planning a comfortable staircase

In addition to min and max Building Code requirements there are a few formulas that can help to design a comfortable, and most importantly, an ergonomic staircase.

The fundamental rule for determining a safe and comfortable rise and run of a staircase is a formula invented by the French architect Francois Blondel in the 17th century, up till now it remains practically unchanged:

Blondel formula : 2×R+ G = 63 - 65 cm,

  • R — step height (rise);
  • G — step width (run, going);
  • 63-65 cm — an average stride length of a person.

There are formulas for designing comfortable staircases among carpenters -  Rule of thumb formulas:

  1. ( Rise + Going ) = 17 ½ - 18 inches (44.45 - 45.72 cm)
  2. ( 2 x Rise + Going ) = 24 - 25 inches (60.96 - 63.5 cm)
  3. (Rise * Going) = 70 – 75 inches (177.8 - 190.5 cm)

According to the first two rules, ideal dimensions of a stair are 7” rise (17.78 cm) and 11” run (27.94cm - almost 28 cm). The stair angle should be 30 – 37 degrees.

 

Building Code and regulations

Now you are aware of main parts of staircase, basic terminology and rules for determining the comfortable stairs. But what is more important is that your design should be compliant with locally adopted Building Codes. There will be big problems in case of not upholding the requirements.

Every country has it’s own building regulations (even every state). So your stair should be compliant with:

  • BCA (Building Code of Australia), if you live in Australia;
  • UK  Building Regulations 2010 Part K, if you live in the United Kingdom
  • IRC (International Residential Code) for dwellings, for commercial stair standards IBC (International Building Code) – stair code of the United States of America
  • NBC (National Building Code of India) – for India.
Stair Rise and Going Dimensions (mm) - BCA (Building Code of  Australia)
Stair Type Rise (R) Going (G) Slope Relationship (2R+G)
Min Max Min Max Min Max
Stairs (other than spiral)115190240355550700
Spiral140220210370590680

The height of a balustrade or other barrier must be not less than 1 m above the floor of any access path, balcony, landing, etc, and not be less than 865 mm above the nosings of the stair treads or the floor of a ramp.

 

Stair Rise and Going Dimensions (mm) - UK Building Regulations 2010 Part K, 2013 edition
Stair Type Rise (R) Going (G) Slope Relationship (2R+G)
Min Max Min Max Min Max
Private Stair 1,2 150220220300550700
Utility Stair150190250400
General Access Stair150170250400

1. The maximum pitch for a private stair is 42°

2. For dwellings, external tapered steps and stairs that are part of the building, the going of each step should be a minimum of 280 mm.

Headroom - at least 2m.

Stair Rise and Going Dimensions (mm) - 2018 IRC (International Residential Code) - USA
Dimension part of IRC 2018 Min Max
metric inches metric inches
Rise (step height)R311.7.5.1102 mm4196 mm7 3/4
Going (run)R311.7.5.2254 mm10
Nosing projectionR311.7.5.319 mm3/432 mm1 1/4
Handrail heightR311.7.8.1864 mm34965 mm38
HeadroomR311.7.22032 mm6 feet 8 inches

  

Stair Rise and Going Dimensions  (mm)  - 2018 IBC (International Building Code) - USA
Dimension part of IBC Min Max
metric inches metric inches
Rise (step height)1011.5.2102 mm4178 mm7   
Going (run)1011.5.2279 mm11
Nosing projection1011.5.5.1-32 mm1 1/4
Headroom1011.32032 mm80-

 

Stair Rise and Going Dimensions (mm) - National Building Code of India, 2016
Dimension part of NBC 2016 Residential buildings Other buildings Low income Housings
Min Min Min Max
Rise (step height)12.18.1.3190 mm150 mm 200 mm
Going (run)12.18.1.2250 mm300 mm225 mm 
Headroom12.18.2220 cm210 cm
Stair width12.18.1.11 m1.5 - 2 m0.6 m

 

When calculating the stairs, a number of parameters must be taken into account, it requires some experience. It is easier to use a special program that simplify calculations. Our service helps to design a staircase much faster, simpler and more efficient, try for free!

 

How to calculate a perfect staircase with Kalk.pro

Choose a stair that suits you according to the type of design, enter the data required for the calculation.

After processing the entered parameters, you get an accurate drawing of the stair, the dimensions of all structural elements, data on the amount of materials needed for the construction. In addition, you get an interactive real 3d staircase model.

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